Cultivation is a microbiological method that propagates and ‘enriches’ any pathogens that may be present in a sample. Pathogens are then detected visually (by seeing the pathogen colonies in organisms growing on the solid medium), microscopically (by pathogen-specific staining and fluorescence microscopy) or molecularly (by PCR detection of pathogen DNA) from the cultured sample. Cultivation is regarded as direct detection of a pathogen, as the cultivability of a sample requires the presence of viable pathogens. In microbiology, the cultivation method is still regarded as the ‘gold standard’ in pathogen detection, even if it is increasingly supplemented or replaced by molecular biological detection methods, such as PCR.
By selecting suitable culture media and conditions then adding antibiotics, individual pathogens or pathogen groups can be specifically selected and enriched. The duration of the cultivation depends on the expected generation time (the time span in which the number of pathogen cells doubles). Compared with other bacteria, such as E. coli (that reproduce within minutes), Borrelia reproduce extremely slowly (several hours per generation); therefore, samples for the detection of Borrelia are cultivated over several weeks (or even months). Other than the relatively long analysis time of the cultivation method, another disadvantage is the detection of pathogens that are difficult or impossible to cultivate, e.g. anaerobes.
These disadvantages are nonetheless offset by clear advantages. The most important advantage of cultivation is the increase of the detection sensitivity of a subsequent PCR analysis by enriching the existing pathogen. In addition, a viable organism is available for further characterisation after successful propagation of the pathogen.
A positive cultivation result provides direct proof of the presence of an infection with the identified pathogen. However, it should be noted that the presence of the pathogen in a sample – and therefore its detectability by cultivation – depends on the corresponding pathogenicity mechanism, which will vary based on the stage of the disease.
Therefore, a culture-based Borrelia detection in blood/serum is only useful in the acute stage of the disease, during reactivation or in cases of doubt. In the chronic stage, however, it is advisable to detect from a tissue sample instead.
The BCA-lab currently uses the cultivation method as a purely experimental procedure. If you are interested, please contact us by telephone.
Material for analysis in the blood:
4 x 4.5 ml S-Monovette (without additives) + specific adapter (material available on request)
Do not centrifuge!
Material for tissue/biopsy analysis:
1 – 3 pieces (>1 mm³) in sterile container with 0.9 % NaCl solution at 4 °C; for longer transport (>24 hours) freeze tissue without liquid in sterile container directly at – 20 °C or – 80 °C.
Analytical test duration:
6 – 12 weeks